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The study shows that bacteria living in the human digestive tract metabolize the compound carnitine, turning it into trimethylamine-N-oxide (TMAO), a metabolite the researchers previously linked in a 2011 study to the promotion of atherosclerosis in humans. Further, the research finds that a diet high in carnitine promotes the growth of the bacteria that metabolize carnitine, compounding the problem by producing even more of the artery-clogging TMAO.

Andbolding mine)

Quoted Text

Additionally, they found specific gut microbe types in subjects associated with both plasma TMAO levels and dietary patterns, and that baseline TMAO levels were significantly lower among vegans and vegetarians than omnivores. Remarkably, vegans and vegetarians, even after consuming a large amount of carnitine, did not produce significant levels of the microbe product TMAO, whereas omnivores consuming the same amount of carnitine did."The bacteria living in our digestive tracts are dictated by our long-term dietary patterns," Hazen said. "A diet high in carnitine actually shifts our gut microbe composition to those that like carnitine, making meat eaters even more susceptible to forming TMAO and its artery-clogging effects. Meanwhile, vegans and vegetarians have a significantly reduced capacity to synthesize TMAO from carnitine, which may explain the cardiovascular health benefits of these diets."

as Lola mentioned!!! It always depends of the taken parameters... that's why I always try to point out why those studies are more then O's do have the most of acids in their stomach... and now tell me.... use your mind please ... what will happen with bacteria and acidity..... = yeehhha you've got it....exactly..... they're gone ... ok perhaps not all if pylorie has embraced you but normally... that's the fact happening

The more I look at this the less clearcut it becomes. Many other elements can convert to Trimethylamine N-oxide besides carnitine, including any and all phospholipids, which are a major component of the cell membrane. Much of this is under the control of the gut flora, but TMAO has some beneficial functions in protein folding and urea metabolism as well. Indeed in some studies its beneficial effects in refolding misfolded proteins were deemed to be cardioprotective.

BTW, there is plenty of TMAO in fish. Its bioconversion is responsible for the 'fishy' odor of non-fresh fish.

I may be wrong and correct me if I am, but the burst in TMAO was observed in humans, but the atherogenicity was observed in mice? Thus the variable, which perhaps is yet to be determined, is the microbiome (floral) variations between the two species. Also, urea itself is cardioprotective, so low urea levels plus high TMAO might have a unique response profile of its own. It's one thing to observe a burst in a chemical after a meal containing a nutrient and quite another to feed 1% of an animal's body weight of that nutrient and observe a disease resulting from it.

Finally blood groups vary significantly in the content of their gut flora.

A whole system is a living system is a learning system.’ -Stewart Brand

I may be wrong and correct me if I am, but the burst in TMAO was observed in humans, but the atherogenicity was observed in mice? Thus the variable, which perhaps is yet to be determined, is the microbiome (floral) variations between the two species.

All the article mentions is this:

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They also examined the cardiac effects of a carnitine-enhanced diet in normal mice compared to mice with suppressed levels of gut microbes, and discovered that TMAO alters cholesterol metabolism at multiple levels, explaining how it enhances atherosclerosis.

Which seems to suggest it is the level of microbes (mouse) that made the difference. I don't know how those microbes compare to human microbes and which of those responsible for the effect are blood-type dependent.

As you say, there is a lot the study doesn't say and there is not enough information here to draw any clear conclusions. One of the conclusions that cannot be drawn is that the study can be dismissed as being 'A' like or some such other thing. We just don't know. This stuff is complicated.

My own observation is that the O or Hunter diet still has less carnitine than what is present in most meat-eating diets because the portions are smaller than most would eat and the frequency is a bit less.

"When in trouble, when in doubt, run in circles - scream and shout." - Anon

Hepatic FMO3 is a known enzymatic source for TMAO in humans, based on the recent recognition of the etiology of an uncommon genetic disorder called trimethylaminuria (also known as fish malodor syndrome)15,17. Subjects with this metabolic condition have impaired capacity to convert TMA, which smells like rotting fish, into TMAO, an odorless stable oxidation product17

the participation of FMOs in human atherosclerosis and HDL cholesterol levels remains to be established. Strong associations between systemic TMAO levels and both angiographic measures of coronary artery atherosclerotic burden and cardiac risks were observed among subjects; however, no correlation was observed between plasma TMAO levels and HDL cholesterol levels in subjects.

Acknowledges that there are other factors.

Overall, just one more puzzle piece. What and how much of this information is of dietary use is not clear to me.

Would secretor status also be an issue to consider in O's since "the overall composition of bacteria in your intestinal ecosysteme" is influenced by secretor status?

I think the answer I would give is probably something along the lines of:

"The information from these studies show additional metabolomics CVD interrelations previously unreported. While there is enough data to warrant further investigation for specific targets or target populations there is limited value of this information for general dietary use".

Yes, secretor status does influence the overall composition of bacteria in your intestinal ecosystem. So do antibiotics, infections/illness, diet/supplements and other natural causes.

Her guests were: Dr. Michael Lauer director of the division of cardiovascular sciences, National Heart, Lung, and Blood Institute (NHLBI) at the National Institutes of Health (NIH).Dr. Stanley Hazen chair of the department of cellular and molecular medicine, Cleveland Clinic's Lerner Research Institute.Duffy MacKay vice president of scientific and regulatory affairs for the Council for Responsible Nutrition.Shalene McNeill executive director of human nutrition research at National Cattlemen's Beef Association (NCBA).

Needless to say, they didn't all agree. Hazen was one of the researchers, but he spent little time on the program.

I can only speak for myself here. I've been following the Type O diet since 2007. I too was afraid of eating meat of any kind but I decided to give it a try and see what happens. What happened was that I have never felt better in my life. I do not take any perscription medications, as do many of the folks that I know who are my age (74) and much younger. My energy level is right up there with folks half my age. I do not suffer from arthritis nor do I get sick very often. In short, I have just followed Dr.D's recommendations for my blood type and I have never been sorry that I did.